SuperWIMP Dark Matter

1. SuperWIMP Dark Matter Jonathan Feng University of California, Irvine University of Washington 4 March 2005

2. Based On… • Feng, Rajaraman, Takayama, Superweakly Interacting Massive Particles, Phys. Rev. Lett., hep-ph/0302215 • Feng, Rajaraman, Takayama, SuperWIMP Dark Matter Signals from the Early Universe, Phys. Rev. D, hep-ph/0306024 • Feng, Rajaraman, Takayama, Probing Gravitational Interactions of Elementary Particles, Gen. Rel. Grav., hep-th/0405248 • Feng, Su, Takayama, Gravitino Dark Matter from Slepton and Sneutrino Decays, Phys. Rev. D, hep-ph/0404198 • Feng, Su, Takayama, Supergravity with a Gravitino LSP, Phys. Rev. D, hep-ph/0404231 • Feng, Smith, Slepton Trapping at the Large Hadron and International Linear Colliders, Phys. Rev. D, hep-ph/0409278

3. Dark Matter • Tremendous recent progress: WDM = 0.23 ± 0.04 • But…we have no idea what it is • Precise, unambiguous evidence for new particle physics

4. SuperWIMPs – New DM Candidate • Why should we care? We already have axions, warm gravitinos, neutralinos, Kaluza-Klein particles, Q balls, wimpzillas, branons, self-interacting particles, self-annihilating particles,… • SuperWIMPs have all the virtues of neutralinos… Well-motivated stable particle Naturally obtains the correct relic density • …and more Rich cosmology, spectacular collider signals There is already a signal

5. G̃ not LSP • Assumption of most of literature • G̃ LSP • Completely different cosmology and phenomenology SM SM NLSP G̃ LSP G̃ SuperWIMPs: The Basic Idea • Supergravity gravitinos: mass ~ MW , couplings ~ MW/M*

6. WIMP ≈ G̃ • Assume G̃ LSP, WIMP NLSP • WIMPs freeze out as usual • But at t ~ M*2/MW3~ month, WIMPs decay to gravitinos Gravitinos are dark matter now: they are superWIMPs, superweakly interacting massive particles

7. SuperWIMP Virtues • Well motivated stable particle. Present in • supersymmetry (supergravity with R-parity conservation) • Extra dimensions (universal extra dimensions with KK-parity conservation) Completely generic: present in “½” of parameter space • Naturally obtains the correct relic density: WG̃ = (mG̃ /mNLSP)WNLSP

8. Other Mechanisms • Gravitinos are the original SUSY dark matter Old ideas: Pagels, Primack (1982) Weinberg (1982) Krauss (1983) Nanopoulos, Olive, Srednicki (1983) Khlopov, Linde (1984) Moroi, Murayama, Yamaguchi (1993) Bolz, Buchmuller, Plumacher (1998) … • Weak scale gravitinos diluted by inflation, regenerated in reheating WG̃< 1 TRH < 1010 GeV • For DM, require a new, fine-tuned energy scale • Gravitinos have thermal relic density • For DM, require a new, fine-tuned energy scale

9. SuperWIMP Signals Typical expectations: • Signals too strong; scenario is completely excluded B) Signals too weak; scenario is possible, but completely untestable Can’t both be right – in fact both are wrong!

10. SuperWIMP Signals • SuperWIMPs escape all conventional DM searches • But late decays t̃→ t G̃,B̃→ gG̃, …,have cosmological consequences • Assuming WG̃ = WDM, signals determined by 2 parameters: mG̃, mNLSP Lifetime Energy release zi = eiBiYNLSP i = EM, had YNLSP = nNLSP / ngBG

11. After WMAP • hD = hCMB • Independent 7Li measurements are all low by factor of 3: • 7Li is now a serious problem Jedamzik (2004) Big Bang Nucleosynthesis Late decays may modify light element abundances Fields, Sarkar, PDG (2002)

12. Best fit reduces 7Li: BBN EM Constraints • NLSP = WIMP  Energy release is dominantly EM (even mesons decay first) • EM energy quickly thermalized, so BBN constrains ( t, zEM ) • BBN constraints weak for early decays: hard g , e- thermalized in hot universe Cyburt, Ellis, Fields, Olive (2002)

13. BBN EM Predictions • Consider t̃→ G̃ t (others similar) • Grid: Predictions for mG̃ = 100 GeV – 3 TeV (top to bottom) Dm = 600 GeV – 100 GeV (left to right) • Some parameter space excluded, but much survives • SuperWIMP DM naturally explains 7Li ! Feng, Rajaraman, Takayama (2003)

14. BBN Hadronic Constraints • BBN constraints on hadronic energy release are severe. Jedamzik (2004) Kawasaki, Kohri, Moroi (2004) • For neutralino NLSPs, hadrons from destroy BBN. Possible ways out: • Kinematic suppression? No, Dm < mZ BBN EM violated. • Dynamical suppression? c = g̃ ok, but unmotivated. • For sleptons, cannot neglect subleading decays: Dimopoulos, Esmailzadeh, Hall, Starkman (1988) Reno, Seckel (1988)

15. BBN Hadronic Predictions Feng, Su, Takayama (2004) Despite Bhad ~ 10-5 – 10-3, hadronic constraints are leading for t ~ 105 – 106, must be included

16. Cosmic Microwave Background • Late decays may also distort the CMB spectrum • For 105 s < t < 107 s, get “m distortions”: m=0: Planckian spectrum m0: Bose-Einstein spectrum Hu, Silk (1993) • Current bound: |m| < 9 x 10-5 Future (DIMES): |m| ~ 2 x 10-6 Feng, Rajaraman, Takayama (2003)

17. SUSY Spectrum (WG̃ = WDM) Feng, Su, Takayama (2004) Shaded regions excluded [ If WG̃ = (mG̃ /mNLSP) WNLSP , high masses excluded ]

18. Model Implications • We’ve been missing half of parameter space. For example, mSUGRA should have 6 parameters: { m0, M1/2, A0, tanb, sgn(m) , m3/2 } G̃ not LSP WLSP > 0.23 excluded G̃ LSP WNLSP > 0.23 ok t̃ LSP excluded t̃ NLSP ok c LSP ok c NLSP excluded Feng, Matchev, Wilczek (2000)

19. Collider Physics • Each SUSY event produces 2 metastable sleptons Spectacular signature: highly-ionizing charged tracks Current bound (LEP): ml̃ > 99 GeV Tevatron Run II reach: ml̃ ~ 180 GeV for 10 fb-1 LHC reach: ml̃ ~ 700 GeV for 100 fb-1 Drees, Tata (1990) Goity, Kossler, Sher (1993) Feng, Moroi (1996) Hoffman, Stuart et al. (1997) Acosta (2002) …

20. Slepton Trapping Slepton trap • Cosmological constraints  • Slepton NLSP • tNLSP < year • Sleptons can be trapped and moved to a quiet environment to study their decays • Crucial question: how many can be trapped by a reasonably sized trap in a reasonable time? Reservoir

21. d D(cosq) Df rin = 10 m, 10 mwe IP Trap Optimization To optimize trap shape and placement: • Consider parts of spherical shells centered on cosq = 0 and placed against detector • Fix volume V (ktons) • Vary ( D(cosq), Df )

22. water Pb Slepton Range • Ionization energy loss described by Bethe-Bloch equation: • Use “continuous slowing down approximation” down to b = 0.05 ml̃ = 219 GeV

23. Model Framework • Results depend heavily on the entire SUSY spectrum • Consider mSUGRA with m0=A0=0, tanb = 10, m>0 M1/2 = 300, 400,…, 900 GeV

24. M1/2 = 600 GeV m l̃ = 219 GeV L = 100 fb-1/yr Large Hadron Collider Of the sleptons produced, O(1)% are caught in 10 kton trap 10 to 104 trapped sleptons in 10 kton trap

25. International Linear Collider L = 300 fb-1/yr By tuning the beam energy, 75% are caught in 10 kton trap 103 trapped sleptons

26. L = 300 fb-1/yr ILC Other nearby superpartners  no need to tune Ebeam

27. What we learn from slepton decays • Recall: • Measurement of G  mG̃ • WG̃. SuperWIMP contribution to dark matter • F. Supersymmetry breaking scale • BBN in the lab • Measurement of GandEl mG̃andM* • Precise test of supergravity: gravitino is graviton partner • Measurement of GNewton on fundamental particle scale • Probes gravitational interaction in particle experiment

28. Recent Related Work • SuperWIMPs in universal extra dimensions Feng, Rajaraman, Takayama, hep-ph/0307375 • Motivations from leptogenesis Fujii, Ibe, Yanagida, hep-ph/0310142 • Impact on structure formation Sigurdson, Kamionkowski, astro-ph/0311486 • Analysis in mSUGRA Ellis, Olive, Santoso, Spanos, hep-ph/0312062 Wang, Yang, hep-ph/0405186 Roszkowski, de Austri, hep-ph/0408227 • Collider gravitino studies Buchmuller, Hamaguchi, Ratz, Yanagida, hep-ph/0402179 Hamaguchi, Kuno, Nakaya, Nojiri, hep-ph/0409248

29. Summary SuperWIMPs – a new class of particle dark matter with novel implications